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THE
PROBLEM OF KNOWLEDGE
A Brief
Introduction to Epistemology
by Jonathan Dolhenty, Ph.D.
PART
TWELVE
IDEAS AND
TERMS (Con't)
Definition
and Division
It has constantly been pointed out that
clearness of ideas is essential to correct
thinking. Vagueness and confusion are the greatest
obstacles to clear thinking in the pursuit of
truth. How many arguments could be quickly settled
if only we made our ideas clear!
Our ideas will be clear when we have an accurate
knowledge of their comprehension and
extension. The comprehension, you will
recall, tells us what the idea implies, what
essential attributes or elements it contains in
itself, and what information it has concerning the
thing it represents.
Again, you will recall that the extension of an
idea gives us the application of the idea to the
individuals, shows us how and in how many objects
the idea is realized, and delimits the extent of
the field in which this idea can be found.
The comprehension and extension of ideas is very
important to understand. Fortunately, there are two
processes that will help us to gauge the
comprehension and extension of ideas: definition
and division.
Definition
A definition is a statement which explains what
a thing is. It answers the question: "What is this
thing?" We can give the answer when we know the
comprehension of the idea which represents this
thing.
There are different kinds of definitions and we
need to be aware of these differences.
We distinguish between nominal
definitions and real definitions. A nominal
definition simply explains what a word means. A
real definition explains what a thing is.
There are many times that a term is unclear or
ambiguous to us. There are times it may be used in
some "technical" sense, for instance in some branch
of empirical science. There are times a particular
speaker or writer wants to use a term in a definite
meaning in order to avoid verbal disputes. In these
cases, a nominal definition is a legitimate
definition.
A real definition, on the other hand, is a
statement explaining what a thing is in itself. A
perfect real definition would be one which briefly
but fully explains the essential nature of a
thing. But there are so many different kinds of
things in the world and things are often too
complex in operation and structure, it is difficult
to distinguish sometimes between their essentials
and nonessentials.
A real definition is an essential definition
when it explains the essence or nature of a thing.
This means we have to define it by its proximate
genus and specific differentia. This would be the
perfect definition.
The proximate genus includes within its
comprehension all the essential elements of the
genera above it and therefore includes all the
things that are similar in nature to the thing
which is to be defined. The specific differentia
brings the distinctive element which separates this
thing from all others of a similar nature, by
showing in what manner it is different from all the
others. This may seem complicated to you but it
really isn't. Just to be sure we're clear on this
matter of proximate genus and specific differentia,
we'll look at an example of this in practice.
A real definition is a descriptive definition
when it explains what a thing is in itself by
enumerating the positive, but nonessential,
elements of its nature.
We must recognize that
certain terms and ideas and things are incapable of
definition. They are known, but not
defined.
Some qualities are so simple they cannot be
analyzed, only experienced. For example, how would
we explain to a blind person what the "red" of a
rose looks like?
Some ideas are so general they cannot be defined
by a strict definition. "Thing," "one," and "being"
are examples.
Rules of
Definition
Certain rules have been devised to ensure that a
definition is correct. Let's take a look at
them.
1. The definition must be clearer than the
thing defined. Metaphorical expressions,
therefore, need to be avoided. In other words,
don't define a "lion" as the "king of beasts."
Metaphors are fine for poetry but not for logical
thinking. Words which are more unusual than the
idea to be explained should be avoided. Don't
define a "lie" as an "intentional terminological
inexactitude."
2. The definition must not contain the idea
to be defined. Don't make a "circular
definition." This is where a first idea is defined
by a second, and then the second is defined by the
first. If we define a "dollar" as "one hundred
cents" and then define a "cent" as "one-hundredth
of a dollar," we would be guilty of a circular
definition.
3. The definition must be convertible with
the idea defined. The definition must not be
wider or narrower in comprehension than the
comprehension of the idea defined. If an "animal"
is a sentient, living, bodily substance," then a
"sentient, living, bodily substance" must be an
"animal." On the other hand, we shouldn't define
"biology" as the "science which studies the world
around us." This is too wide a definition since
other sciences also study the world around us. We
shouldn't define "biology" as the "science which
studies animals," because it is too narrow. Biology
also studies plants.
4. Finally, the definition must be positive,
not negative, whenever possible. A definition
should explain what a thing is; not what it is not.
"Health" is not the absence of sickness. I can't
know what sickness is without prior knowledge of
what "health" means.
Division
Besides definition, we have a second method of
making ideas clear and arriving at a better
understanding of their meaning. This method is
called division.
Division means the resolving of a whole into its
parts. Something is "whole" when it consists of
parts which are bound together into some sort of
unity. Since the "whole" consists of parts, it can
be broken up (resolved) into these component parts.
There are two kinds of division.
A real division is the resolution of a
thing into the natural parts which it has
independent of the mind. If these parts are
physical, we have a physical division. If the parts
are metaphysical, we have a metaphysical
division.
Rules of
Division
Logicians have certain rules which must be
observed in division so that it fulfills its
purpose of making ideas clear and accurate for
science and for general knowledge. Here are the
rules:
Rule 1. A division should be adequate.
This means that all the parts taken together must
equal the whole. There are a number of sections to
this rule.
- No part may be omitted or the division is
incomplete and faulty. Think, for instance, of
the term "American politician." If we divided
this term into Democrats and Republicans, the
division would be inadequate because some
politicians, such as Socialists, Libertarians,
Progressives, and so forth, would be
omitted.
- No member of the division may equal or
exceed the whole. A part can never equal and
certainly cannot exceed the whole. It would be
improper to divide the term "animals" into
sentient and rational because sentient is the
same as or equal to animal.
- No member may include the other. The parts
must be distinct and exclusive among themselves.
Such a division would enumerate more parts than
the whole really contains. It would be incorrect
to divide "Immigrants to America" into
Englishmen, Germans, Europeans, Japanese,
Asians, and Mexicans, because Englishmen and
Germans are already included in the class of
"Europeans" and Japanese are already included in
the class of "Asians."
Rule 2. The division should be clear.
Here are the sections pertaining to this rule.
- A division should be orderly. We must not
leap from a higher to a lower class and omit a
middle class. The division should be a gradual
process. It would be improper to divide
"animals" into men, birds, reptiles, insects,
fish, and mammals, because the next members of
the class of "animals" are human beings and
nonhuman animals.
- A division should be reasonably limited in
members. To divide "insects" by producing a list
of the thousands of names of insects would be
ridiculous. Fortunately, empirical science
enters the picture here with its taxonomic
classifications whereby it organizes numerous
insects, birds, and other animals into main
classes, subclasses, and so on. This is an
excellent example of science bringing order out
of chaos.
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